EP0441929B1 - Device for extruding multilayer plastic films or plates - Google Patents

Abstract

The invention relates to a process for extruding multilayer plastic films or plates with broad-apertured nozzle comprising a coathanger-shaped broadening (8) in the melt feed line (7) in the nozzle body (1) in front of the nozzle aperture (9) and a feed block (17) at least partly integrated in the nozzle body (1), the inlets (11) of which are fed with different plastic melts by at least two extruders and which takes these melts to a block (3) with slots (4, 5, 6) acting as its outlet, in which the block (3) is arranged as closely as possible in front of the inlet of the coathanger-shaped broadening (8), is designed as a separate part-block of the feed block (17) and, as such, is interchangeably arranged both individually and with the entire feed block (17) substantially parallel to the direction of flow of the plastic melts in relation to the nozzle body (1), has externally operable means (20 - 25) for varying the cross-section of the outermost of the slots (4) arranged parallel to the nozzle aperture (9), e.g. by thrust rods (21) or taper drives (24) actuating adjusting screws (22) or drives (25), and has further slots (5, 6) arranged perpendicularly to said slots (4) without crossing them.

Description

Device for extruding plastic multilayer films or sheets

The invention relates to a device for extruding plastic multilayer films or sheets according to the features of the preamble of main claim 1.

Such devices are known, for example, from a publication in "Modern Plastics", Aug. 83, pp. 22-26 or also an advertisement in "Kunststoffe", 8/88, p. A33. In both cases, between several extruders, each of which produces a plastic melt, and the die body of a slot die, a feed block, which can be replaced with more or less effort, is connected, which receives a plastic melt at its inputs and this via a system of internal channels to a block serving as an outlet conducts with slot-like bushings, which in turn emits a strand of molten plastic with a sandwich-like layer structure and preferably a rectangular cross-section. This strand then travels in a suitable cross-section at least partially in the nozzle body and more or less in length - due to the design - up to a hanger-like extension of the melt line running in the nozzle body, before it extends the strand with widening and flattening while at the same time maintaining the sandwich-like layer structure in the slot-like manner Output slot of the slot die - if necessary after merging with other plastic layers - feeds. The feed block can be externally accessible means for mechanically regulating the layer thicknesses of the individual layers of plastic melts or also of the whole Have strands in the feed block, for example flaps, dust bars or throttle shafts with a non-rotationally symmetrical circumference that can be moved via bolts or set screws.

In such devices, it proves to be advantageous that the associated feed block is accessible from all sides on the one hand, and on the other hand is provided with means for regulating the different layer thicknesses of the plastic melts, because on the one hand in principle for each desired layer structure - both in material and in terms of arrangement special feed block is required and therefore the simplest possible replacement of the same or at least essential parts of them is extremely desirable and on the other hand certain fluctuations in the temperatures and / or viscosities of the individual plastic melt layers, which lead to fluctuations in the layer structure of the end product, are inevitable and with the means described above can be corrected.

Such a correction, however, requires considerable experience of the operating personnel in the case of the disclosures of the aforementioned publications, since here the layer thickness of each plastic melt layer can be changed individually, but the neighboring layer (s) on the one hand and consequently the entire layer structure on the other hand are always influenced, so that a clear correction requires a very precise coordination of all available correction options, which places ever increasing demands on the experience of the operating personnel with an increasing number of layers. Apart from the fact that as the number of layers increases, the construction of the corresponding feed block becomes more and more demanding and expensive.

Another disadvantage of the devices described is that precisely because of the easily accessible feed block from the point at which the various layers of the plastic melt are brought together in the feed block to the entrance into the hanger-like extension of the melt line in the nozzle body - regardless of whether the feed block is connected directly or with the interposition of further line elements to the nozzle body - need a channel of noticeable length, since the coat hanger-like extension in the nozzle body for reasons of stability of this nozzle body does not directly to one of the outer walls of this nozzle body which does not have the exit gap and thus to the connection point of the feed line of the strand the plastic melt can reach from the feed block to the nozzle body. In practice, however, it has been found that by no means all conceivable layer structures of plastic melts necessarily flow in a strictly laminar manner in such a channel, but that mixing and / or swirling of individual pairs of plastic melts already occur at the respective layer boundary, which in any case does not occur in the hanger-like extension reform and allow an undefined end product to emerge, which can no longer be corrected by external manipulations of means for regulating the melt flow of individual or all plastic melt layers in the feed block.

The aforementioned disadvantage is avoided by a nozzle arrangement according to US Pat. No. 4,619,802, in which the input part of a feed block is replaced by fixed bores in the rear of the nozzle body, arranged essentially in the direction of flow of the plastic melts, and the remaining front part of the feed block is perpendicular to the direction of flow Plastic melts are inserted into a corresponding recess in the nozzle body, this interchangeable feed block part likewise Has means for mechanically regulating the layer thicknesses of the individual plastic melt layers, the actuation of which influences both the neighboring layer (s) and the entire layer structure. The advantage of this nozzle arrangement lies in the fact that the exit of the interchangeable feed block part can be placed very close to the entrance of the hanger-like extension of the melt line, which widens the stratified melt flow by widening in the direction parallel to the nozzle mouth while constricting in the perpendicular direction while maintaining the layer structure leads to the nozzle mouth. A disadvantage of this arrangement, however, is that because of the means used to regulate the layer thicknesses in the form of a flap which can be rotated between the layers, for the reasons already mentioned only for layer structures with very few - according to the disclosure of the aforementioned publication even with only two - Layers can be used - unless a multi-channel nozzle with one or more of the aforementioned modifications of a feed block is to be used. In addition, the aforementioned arrangement requires a very deep nozzle body in order to be able to install the replaceable feed block part behind the hanger-like extension on the one hand and the holes for connecting the extruders to the aforementioned feed block part through the rear wall of the nozzle body in the latter, and also considerably limits the Flexibility of the feed blocks originally disclosed in the publications cited on p. 1, paragraph 2 in that the number and distribution of the plastic melts on the slot-like feedthroughs in the exchangeable feed block part are largely determined by the holes in the rear of the nozzle body, while otherwise by the simple replacement of a complete feed block outside the nozzle body makes it possible to generate any possible layer structure with the same nozzle body.

The limitation of the number of plastic melts to be combined in the feed block due to the means used to mechanically regulate the layer thicknesses both in the objects of the publications cited on p. 1, paragraph 2 and in the subject of the aforementioned US Pat. No. 4,619,802 can be according to the publication Avoid "new packaging" 6/78, pp. 842 - 848, in particular p. 847, right column, by using a feed block that consists of a compact block in its output area with a large number of parallel slot-like feedthroughs, this block on the one hand not providing any means for mechanically regulating the layer thicknesses of the individual plastic melt layers, and several parallel slot-shaped feedthroughs can also be used to form a single plastic melt layer, which, as is known, can result in rheological advantages in the formation of the layered melt flow formed overall by the feed block. Experience has shown that with a suitable arrangement of the slot-like feedthroughs of such a feed block for each special case of a desired layer structure in connection with the simple interchangeability of this feed block in the path between the extruder and the nozzle body, the use of additional means for mechanically regulating the layer thicknesses of the individual plastic melts Layers in any case superfluous for the inner layers. Only the formation of the two outer cover layers remains unsatisfactory, especially if they are to be very thin, since these are subject not only to compensation processes with neighboring plastic melt layers, but also to those with the inner walls of the melt line, in particular those of its hanger-like extension, which at least in some cases it appears desirable to be able to readjust their training.

The fact that each means by means of a Wide-slot nozzle produced plastic multilayer film or plate because of the inevitable constriction from the sides after leaving the nozzle mouth initially has an undesirable edge deformation, which is usually eliminated by suitable trimming. However, this results in a considerable amount of waste, which should usefully be returned to the production process of the plastic multilayer film or sheet, but because of its composition from all layers of the previously produced product, generally only with special measures - as described, for example, in DE OS 36 04 004 can be described - can be subjected to a suitable recycling process.

The present invention is therefore based on the object of further developing the known generic devices such that while maintaining the flexibility of a generic device with regard to the number of layers to be produced and the variation of the layer structure formed, as well as achieving the smallest possible distance between the output of the feed block and the entrance of the hanger-like extension of the melt line in the nozzle body with the simplest and cheapest possible means a clearly defined layer structure of layers of a plastic multilayer film or plate arranged in parallel with any number of layers can be generated, and in addition a simple recycling of the edge trimming waste generated from the nozzle outlet is enabled.

The invention achieves this with the aid of the features of the characterizing part of main claim 1.

A particular advantage of this invention is given in that the interchangeable feed block due to the Possibility of replacement in the direction of flow of the plastic melts with simple constructive measures for each common nozzle body of a single or multi-channel slot die so that its outlet can be arranged as close as possible to the entrance of the hanger-like extension of the melt line in the nozzle body, for which purpose only the existing one Melt line expanded accordingly and a suitable simple mechanical holder for the part of the feed block that is not immersed in the nozzle body can be attached to the rear of the nozzle body. On the other hand, in this construction, the flexibility with regard to the interchangeability of feed blocks on a nozzle body with respect to the objects of the publications cited on p. 1, paragraph 2 is also fully retained. This flexibility is advantageously increased further in that the block with slot-like feedthroughs and the rest of the feed block represent at least two separate sub-blocks of the feed block, because in this case, for example, only the block with slot-like feedthroughs has to be replaced when the layer structure, ie the number, The arrangement and the respective layer thickness should remain unchanged, but a change in the starting materials, for rheological reasons, makes a changed arrangement of the slot-like bushings necessary or at least desirable for one or more of the plastic melt layers.

A further advantage of the present invention is based on the fact that it has externally operable means for cross-sectional variation of the outermost of the slot-like bushings - arranged parallel to the nozzle mouth - since experience has shown that the mutual influence of the flow behavior of the inner layers of a layered plastic melt strand after Once a suitable parameter selection has been determined, it is not taken into account within relatively wide limits may remain, but the outermost layers may have larger irregularities in the flow behavior because of their interaction both with a molten neighboring layer and with a wall surface of the nozzle body, which make an immediate readjustment appear very desirable.

Of particular advantage in the present invention is the attachment of further slot-type bushings in the block provided, which run perpendicularly and without crossing to the existing slot-type bushings - arranged parallel to the nozzle mouth - because this makes it possible to seal the edges in this way of the multilayer films or sheets to be produced so that the edge trimming normally to be carried out after these products emerge from the nozzle mouth only produces waste from a single plastic component, which can then be returned to the corresponding extruder of the overall device without special additional measures.

In an advantageous embodiment of the device according to the invention, the block forming the output of the at least two-part feed block with slot-like bushings with at least partially removed remainder of the feed block, which contains the entrances connected to extruders and the connecting channels from these entrances to the slot-like bushings, is fitted into one recess open on one side in the rear wall of the nozzle body - possibly with supportive means for insertion and / or removal - inserted and, if necessary, also removed from it. In this case, threaded bores can advantageously be used as supporting means for inserting and / or removing again, for example, threaded bores made in the free surface of the block with the slot-like bushings remaining after the insert or -bolts as points of attack for hand or machine-operated gripping devices for moving the block with the slot-like bushings relative to the nozzle body.

In a further advantageous embodiment of the device according to the invention, the nozzle body is provided with suitable special bushings, by means of which the externally actuatable means on the block of the slot-like bushings are brought into engagement with manipulators in the outer space of the nozzle body after inserting this block into the corresponding recess in the nozzle body, in order to be able to influence the flow behavior of the outermost layers of the multilayer films or sheets to be produced in a simple manner.

In another advantageous embodiment of the device according to the invention, the one-part or multi-part feed block is inserted in one piece into a recess of the nozzle body which is open on three sides, or is removed from it again, in which case two sides of the feed block and in particular the block contained therein with slot-like bushings are accessible in this way remain that here the externally accessible means for controlling the melt flow of the outermost plastic melt layers can be actuated directly in the area of the block with the slot-like bushings. Such means for controlling the melt flow can advantageously be used, for example, parallel to the slot-like bushings and perpendicular to the direction of flow of the respective plastic melt layer, dust bars actuated by set screws or wedge gears operated by set screws or drives.

Embodiments of the device according to the invention are shown in the drawing.

Fig.: 1

Aufsicht auf den Schnitt durch eine schematische Darstellung einer erfindungsgemäßen Breitschlitzdüse in deren Mittelebene mit teilweise integriertem und teilweise entferntem Feedblock - partiell in durchbrochener Darstellung.

Fig. 2:

Schnitt A-A aus Fig. 1 nach Ergänzung der erfindungsgemäßen Breitschlitzdüse durch ihren in Fig. 1 oberhalb der Bildebene zu ergänzenden Teil in geändertem Maßstab - teilweise in durchbrochener Darstellung.

Fig. 3:

Mittelabschnitt des Schnittes B-B aus Fig. 1 nach Ergänzung der erfindungsgemäßen Breitschlitzdüse gemäß Fig. 2 in geändertem Maßstab - gesehen in Richtung des Pfeiles D in Fig. 1.

Fig. 4:

Mittelabschnitt des Schnittes C-C aus Fig. 1 nach Ergänzung der erfindungsgemäßen Breitschlitzdüse gemäß Fig. 2 im gleichen Maßstab wie Fig. 3 - gesehen in Richtung des Pfeiles E in Fig. 1.

Fig. 5:

Weitere mögliche Ausführungsform einer erfindungsgemäßen Breitschlitzdüse mit einem im Ganzen integrierten Feedblock in einer der Fig. 1 entsprechenden Darstellung.

Fig. 6:

Erfindungsgemäße Breitschlitzdüse der Fig. 5 in einer der Fig. 2 entsprechenden Darstellung (Schnitt A-A).

Fig. 7:

Mittelabschnitt des Schnittes B-B aus Fig. 5 in geändertem Maßstab.

Fig. 8:

Vergrößerte Darstellung der Fig. 2 mit speziellen Durchführungen vom Außenraum der Düsenkörper zum Block mit schlitzartigen Durchführungen zur Betätigung von Mitteln zum Steuern des Schmelzeflusses der äußersten Kunststoffschmelze-Schichten im vorgenannten Block.

Show it:

Fig .: 1

Top view of the section through a schematic representation of a slot die according to the invention in its central plane with a partially integrated and partially removed feed block - partially in a broken line.

Fig. 2:

Section AA of FIG. 1 after supplementing the slot die according to the invention by its part to be supplemented in FIG. 1 above the image plane, on a changed scale - partly in a broken line.

Fig. 3:

Middle section of section BB from FIG. 1 after addition of the slot die according to the invention according to FIG. 2 in a modified scale - seen in the direction of arrow D in FIG. 1.

Fig. 4:

Middle section of section CC from FIG. 1 after addition of the slot die according to the invention according to FIG. 2 on the same scale as FIG. 3 - seen in the direction of arrow E in FIG. 1.

Fig. 5:

Another possible embodiment of a slot die according to the invention with a feed block integrated as a whole in a representation corresponding to FIG. 1.

Fig. 6:

5 in a representation corresponding to FIG. 2 (section AA).

Fig. 7:

Middle section of the section BB of Fig. 5 in a changed scale.

Fig. 8:

2 with special bushings from the outside of the nozzle body to the block with slot-like bushings for actuating means for controlling the melt flow of the outermost plastic melt layers in the aforementioned block.

Fig. 1 shows a plan view of the section through a schematic representation of a slot die according to the invention in the central plane of the lower half of a two-part nozzle body 1 with half a chamber-like recess 2 for the fitting reception of a part of a complete feed block, separable from it and cut here Block 3 shown with slot-like bushings 4, 5, 6, with a melt line 7 adjoining this recess 2, shown here only as a one-sided depression, and with a hanger-like extension 8 of the melt line 7, also shown here only as a one-sided depression, which extends into a slot-like exit gap , the nozzle mouth 9, runs out. On the side of the block 3 facing away from the melt line 7, a frame 10 is non-positively attached to the nozzle body 1 in a known manner, which, on the one hand, is to be thought after the half of a slot die shown in FIG. 1 has been supplemented by the one above that shown in FIG. 1 Part of a complete slot die does not prevent the block 3 from being removed from the recess 2, which on the other hand is provided with connections 11 for the feed lines of the plastic melts supplied by extruders (not explicitly shown here) and which, in the case shown, also has a two-sided open, fitting-shaped space 12 for the Inserts the part of a feed block that is assumed to be removed and not shown here, which conducts the plastic melts from the extruder connections 11 to the slot-like bushings 4, 5, 6 in a known manner by means of suitable channels running in it.

Fig. 2 with the same reference numerals shows the same device as Fig. 1 on a different scale from another side, but in the same state, i.e. the moment a feedblock is replaced. The connecting part of the feed block from the extruder connections 11 to the slot-like bushings 4, 5, 6 is already removed from the space 12 spanned by one side of the block 3 and the frame 10. In block 3, threaded bolts 14 are briefly screwed into threaded bores 13, which serve as points of attack for a hand or machine-operated gripping device for pulling block 3 out of recess 2. After the block 3 has been pulled out sufficiently far from the recess 2, it is led out of the space 12 laterally. Subsequently, a new block 3 is inserted in the recess 2 with the help of threaded bolts 14, the threaded bolts 14 are unscrewed and a new connecting part between the extruder connections 11 and the slot-like bushings 4, 5, 6 is used to complete the required feed block in the Room 12 inserted, the necessary locking means of a known type and are therefore not explicitly shown here. This means that a new production cycle for the production of a plastic multilayer film or sheet can be started.

3 and 4 show the input and the output side of the block 3 with respect to the plastic melts passed through it for the same device and in the same state as in FIG. 2, only on a different scale. In Fig. 3 are in particular the slot-like bushings 4, 5, 6 and the heads of the threaded bolts 14 anchored in the threaded bores 13 and additionally the parting plane 15 of the halves of the nozzle body 1 and the stop surfaces 16 of the frame 10 on the nozzle body 1 which are marked here only for the sake of clarity. 4, on the other hand, it can be seen in particular that the circumference of the melt line 7, which is reduced by the area marked specifically for the sake of clarity and is shown here interrupted, is significantly smaller than the circumference of the block 3 shown in solid lines, so that a clear stop surface is formed here. Both FIGS. 3 and 4 clearly disclose a set of slit-like bushings 4, 5, 6, in which, in addition to a set of parallel slit-like bushings 4, to produce the desired layer structure of the plastic multilayer film or sheet to be produced, one each perpendicular to the side of this set the slot-like bushings 4, the slot-like bushing 5, 6 for producing an edge seal of the plastic multilayer film or sheet to be produced is incorporated into the block 3.

FIG. 5 shows, in a representation corresponding to FIG. 1, another possible exemplary embodiment of a slot die according to the invention, in which the feed block 17 is integrated as a whole into the nozzle body 1 of the slot die. The main difference here compared to FIG. 1 is that on the one hand - as can be seen in particular from FIG. 6 - the recess 18 for receiving the complete feed block 17 is of a tab-like shape which is open on three sides, and that on the other hand also the extruder connections 11 with the slot-like ones in the present case Feedthroughs 4, 5, 6 connecting connecting channels 19 extending in the feed block 17 can be seen.

FIG. 6 shows the device of FIG. 5 in a representation corresponding to FIG. 2, with on the one hand in particular - as already explained above 5 - the three-sided open tab-like shape of the recess 18 from FIG. 5 can be seen, whereby on the other hand the connecting channels 19 coupling the extruder connections 11 with the slot-like bushings 4, 5, 6 and extending in the feed block 17 are clearly disclosed and use is also made of the use of externally accessible means for regulating the melt flows of the outermost plastic melt layers 4 in the block 3 with the slot-like bushings 4, 5, 6. In the upper edge region of the block 3 with the slot-like bushings 4, 5, 6, a dust bar 21 oriented transversely to the melt flow is installed in a cavity 20 adjacent to the top slot-like bushing 4 Implementation 4 and thus the melt flow passing through it changed. In the lower edge area of the block 3, on the other hand, a wedge gear 24 is installed - not mandatory, but for reasons of a brief disclosure - in a corresponding cavity 23, which via actuation of an actuator 25 oriented parallel to it via a rigid coupling (driver 29) through a slot 28 in block 3 through the cross section of the bottom slot-like bushing 4 and thus the melt flow passing through it changed.

The construction of the aforementioned means for regulating the melt flow in the outermost slot-like feedthroughs 4 in the block 3 is shown again in FIG. 7 on an enlarged scale and from another side. In particular, a possible embodiment of a wedge gear 24 is explicitly shown, which consists of a wedge 26 arranged transversely to the direction of flow of the plastic melt streams and firmly connected to the block 3 and a wedge 27 which can be moved in the same direction but with an opposite rise in the cavity 23, wherein the drive of the movable wedge 27 in the illustrated Case by an actuator 25 arranged outside the block 3 transversely to the flow direction of the plastic melt streams in the form of a spindle drive and the coupling of the movable wedge 27 to the actuator 25 via a rigid, provided with a threaded bore for the spindle of the actuator 25, through a slot 28 engaging in block 3 and frictionally connected with the wedge 27 driver 29 takes place.

The replacement of a feed block 17 on the device shown in FIGS. 5 to 7 only requires the use of suitable extruder connections and locking means of a known type, which are not explicitly shown here.

8 shows an enlarged illustration of FIG. 2 with special bushings 30 in the nozzle body 1 for receiving coupling devices 31 for actuating the means 20-22 installed on the block 3 of the slot-like bushings 4, 5, 6 for controlling the flow of the outermost plastic melt. Layers 4 through the block 3 from the outside of the nozzle body 1.

Reference list

1

Nozzle body

2, 18

Recesses

3rd

block

4, 5, 6

slot-like bushings

7

Melting line

8th

hanger-like extension

9

Nozzle mouth

10th

frame

11

Extruder connections

12th

Space for part of a feed block

13

Tapped holes

14

Threaded bolt

15

Parting plane of the nozzle body halves

16

Abutment surfaces

17th

Feedblock

19th

Connecting channels

20, 23

Cavities

21

Dust bar

22

Set screw

24th

Wedge gear

25th

Actuator

26, 27

Wedges

28

slot

29

Carrier

30th

Implementations

31

Coupling devices

Claims (8)

1. Apparatus for extruding multi-layer plastics films or plates, comprising at least two extruders for producing different plastics melts, an exchangeable feed block (17) whereof the inlets (11) are each fed with a plastics melt by the extruders and which guides the plastics melts from its inlets to a block (3) forming its outlet and having slot-type passageways (4, 5, 6), and a die body (1) in which the extrudate of plastics melts emerging from the said block (3) and having a sandwich-type layer structure is supplied by means of a coathanger-type widened section (8) of the melt line running therein, while maintaining the layer structure, to the slot-type outlet gap (9) of a broad-slot die, the feed block (17) being at least partially integrated in the die body (1) such that the melt line between the outlet of the feed block (17) and the inlet of the coathanger-type widened section (8) is as short as possible, characterized in that the block (3) having slot-type passageways (4, 5, 6) represents a separate part block of the overall feed block (17), this part block being formed to be replaceable both individually and also as a component of the overall feed block (17) within the overall apparatus, the block (3) being introduced into and removed from the die body (1) substantially parallel to the direction of flow of the plastics melts, this part block having, in addition to a plurality of slot-type passageways (4) which are aligned parallel to the slot-type outlet gap (9) of the broad-slot die, that is to say parallel to its die mouth (9), and which are substantially invariable in their cross-sectional dimensions, further slot-type passageways (5, 6) which are arranged perpendicular to and without intersecting the said passageways (4), and the part block possessing externally actuable means (20 - 29) for varying the cross-section of the respectively outermost of the said passageways (4).
2. Apparatus for extruding multi-layer plastics films or plates according to Claim 1, characterized in that the block (3) having the slot-type passageways (4, 5, 6) can be introduced fittingly into a recess (2) of the die body (1) open on one side when the rest of the feed block (17) is at least partially removed, and can also be removed therefrom again.
3. Apparatus for extruding multi-layer plastics films or plates according to Claim 2, characterized in that the block (3) which is constructed as a separate part block and has the slot-type passageways (4, 5, 6) is provided with means which assist both the introduction of this block (3) into and also the re-removal of this block (3) from the recess (2) of the die body (1) which is open on one side.
4. Apparatus for extruding multi-layer plastics films or plates according to Claim 3, characterized in that the means for assisting the introduction or re-removal of the separate block (3) having the slot-type passageways (4, 5, 6) into or from the recess (2) of the die body (1) open on one side are threaded bores (13) in the freely accessible surface of the block (3) having the slot-type passageways (4, 5, 6) which is left after introduction, these threaded bores (13) serving to temporarily receive threaded rods or threaded pins (14) as action points for manually or machine operated gripping apparatus for moving the block (3) having the slot-type passageways (4, 5, 6) relative to the die body (1).
5. Apparatus for extruding multi-layer plastics films or plates according to one of the preceding Claims 1 to 4, characterized in that the die body (1) has special passageways (30) for externally actuable means (20 - 22) for cross-sectional variation of the respectively outermost of the said passageways (4).
6. Apparatus for extruding multi-layer plastics films or plates according to Claim 1, characterized in that the overall feed block (17) can be introduced fittingly into a recess (18) of the die body (1) which is open on three sides and can also be removed therefrom again.
7. Apparatus for extruding multi-layer plastics films or plates according to one of the preceding Claims 1 - 6, characterized in that the means for cross-sectional variation of the respectively outermost of the said passageways (4) are setscrews (22) acting on restricting bars (21) which are arranged parallel to the slot-type passageways (4) and transversely to the direction of flow of the plastics melt layers.
8. Apparatus for extruding multi-layer plastics films or plates according to one of the preceding Claims 1 - 6, characterized in that the means for cross-sectional variation of the respectively outermost said passageways (4) are setscrews or tangent screws (25) acting on wedge gears (24) arranged parallel to the slot-type passageways (4) and transversely to the direction of flow of the plastics melt layers.

Images